From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Jason Baron <jbaron@akamai.com>, Jiri Kosina <jkosina@suse.cz>,
David Laight <David.Laight@ACULAB.COM>,
Borislav Petkov <bp@alien8.de>, Julia Cartwright <julia@ni.com>,
Jessica Yu <jeyu@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64
Date: Tue, 27 Nov 2018 09:43:30 +0100 [thread overview]
Message-ID: <20181127084330.GX2113@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181126212628.4apztfazichxnt7r@treble>
On Mon, Nov 26, 2018 at 03:26:28PM -0600, Josh Poimboeuf wrote:
> Yeah, that's probably better. I assume you also mean that we would have
> all text_poke_bp() users create a handler callback? That way the
> interface is clear and consistent for everybody. Like:
Can do, it does indeed make the interface less like a hack. It is not
like there are too many users.
> diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
> index aac0c1f7e354..d4b0abe4912d 100644
> --- a/arch/x86/kernel/jump_label.c
> +++ b/arch/x86/kernel/jump_label.c
> @@ -37,6 +37,11 @@ static void bug_at(unsigned char *ip, int line)
> BUG();
> }
>
> +static inline void jump_label_bp_handler(struct pt_regs *regs, void *data)
> +{
> + regs->ip += JUMP_LABEL_NOP_SIZE - 1;
> +}
> +
> static void __ref __jump_label_transform(struct jump_entry *entry,
> enum jump_label_type type,
> void *(*poker)(void *, const void *, size_t),
> @@ -91,7 +96,7 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
> }
>
> text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE,
> - (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
> + jump_label_bp_handler, NULL);
> }
>
> void arch_jump_label_transform(struct jump_entry *entry,
Per that example..
> diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
> index d3869295b88d..e05ebc6d4db5 100644
> --- a/arch/x86/kernel/static_call.c
> +++ b/arch/x86/kernel/static_call.c
> @@ -7,24 +7,30 @@
>
> #define CALL_INSN_SIZE 5
>
> +struct static_call_bp_data {
> + unsigned long func, ret;
> +};
> +
> +static void static_call_bp_handler(struct pt_regs *regs, void *_data)
> +{
> + struct static_call_bp_data *data = _data;
> +
> + /*
> + * For inline static calls, push the return address on the stack so the
> + * "called" function will return to the location immediately after the
> + * call site.
> + *
> + * NOTE: This code will need to be revisited when kernel CET gets
> + * implemented.
> + */
> + if (data->ret) {
> + regs->sp -= sizeof(long);
> + *(unsigned long *)regs->sp = data->ret;
> + }
> +
> + /* The exception handler will 'return' to the destination function. */
> + regs->ip = data->func;
> +}
Now; if I'm not mistaken, the below @site is in fact @regs->ip - 1, no?
We already patched site with INT3, which is what we just trapped on. So
we could in fact write something like:
static void static_call_bp_handler(struct pt_regs *regs, void *data)
{
struct static_call_bp_data *scd = data;
switch (data->type) {
case CALL_INSN: /* emulate CALL instruction */
regs->sp -= sizeof(unsigned long);
*(unsigned long *)regs->sp = regs->ip + CALL_INSN_SIZE - 1;
regs->ip = data->func;
break;
case JMP_INSN: /* emulate JMP instruction */
regs->ip = data->func;
break;
}
}
> void arch_static_call_transform(void *site, void *tramp, void *func)
> {
> @@ -32,11 +38,17 @@ void arch_static_call_transform(void *site, void *tramp, void *func)
> unsigned long insn;
> unsigned char insn_opcode;
> unsigned char opcodes[CALL_INSN_SIZE];
> + struct static_call_bp_data handler_data;
> +
> + handler_data.func = (unsigned long)func;
>
> - if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE))
> + if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE)) {
> insn = (unsigned long)site;
> + handler_data.ret = insn + CALL_INSN_SIZE;
> + } else {
> insn = (unsigned long)tramp;
> + handler_data.ret = 0;
> + }
handler_data = (struct static_call_bp_data){
.type = IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) ? CALL_INSN : JMP_INSN,
.func = func,
};
> mutex_lock(&text_mutex);
>
> @@ -52,14 +64,9 @@ void arch_static_call_transform(void *site, void *tramp, void *func)
> opcodes[0] = insn_opcode;
> memcpy(&opcodes[1], &dest_relative, CALL_INSN_SIZE - 1);
>
> /* Patch the call site: */
> text_poke_bp((void *)insn, opcodes, CALL_INSN_SIZE,
> + static_call_bp_handler, &handler_data);
>
> done:
> mutex_unlock(&text_mutex);
next prev parent reply other threads:[~2018-11-27 8:44 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 13:54 [PATCH v2 0/4] Static calls Josh Poimboeuf
2018-11-26 13:54 ` [PATCH v2 1/4] compiler.h: Make __ADDRESSABLE() symbol truly unique Josh Poimboeuf
2018-11-27 8:49 ` Ard Biesheuvel
2018-11-26 13:54 ` [PATCH v2 2/4] static_call: Add static call infrastructure Josh Poimboeuf
2018-11-26 13:54 ` [PATCH v2 3/4] x86/static_call: Add out-of-line static call implementation Josh Poimboeuf
2018-11-26 15:43 ` Peter Zijlstra
2018-11-26 16:19 ` Steven Rostedt
2018-11-26 13:55 ` [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64 Josh Poimboeuf
2018-11-26 16:02 ` Peter Zijlstra
2018-11-26 17:10 ` Josh Poimboeuf
2018-11-26 17:56 ` Josh Poimboeuf
2018-11-26 20:00 ` Peter Zijlstra
2018-11-26 20:08 ` Peter Zijlstra
2018-11-26 21:26 ` Josh Poimboeuf
2018-11-27 8:43 ` Peter Zijlstra [this message]
2018-11-27 8:50 ` Peter Zijlstra
2018-11-29 6:05 ` Andy Lutomirski
2018-11-29 9:42 ` Peter Zijlstra
2018-11-29 13:11 ` Josh Poimboeuf
2018-11-29 13:37 ` Andy Lutomirski
2018-11-29 14:38 ` Peter Zijlstra
2018-11-29 14:42 ` Jiri Kosina
2018-11-29 16:33 ` Josh Poimboeuf
2018-11-29 16:49 ` Peter Zijlstra
2018-11-29 16:59 ` Andy Lutomirski
2018-11-29 17:10 ` Josh Poimboeuf
2018-11-29 22:01 ` Peter Zijlstra
2018-11-29 22:14 ` Josh Poimboeuf
2018-11-29 22:22 ` Peter Zijlstra
2018-11-29 22:25 ` Andy Lutomirski
2018-11-29 22:30 ` Josh Poimboeuf
2018-11-29 17:15 ` Peter Zijlstra
2018-11-29 17:20 ` Steven Rostedt
2018-11-29 17:21 ` Steven Rostedt
2018-11-29 17:41 ` Andy Lutomirski
2018-11-29 17:45 ` Josh Poimboeuf
2018-11-29 17:52 ` Andy Lutomirski
2018-11-29 17:49 ` Steven Rostedt
2018-11-29 18:37 ` Josh Poimboeuf
2018-11-29 16:50 ` Linus Torvalds
2018-11-29 16:55 ` Steven Rostedt
2018-11-29 17:02 ` Andy Lutomirski
2018-11-29 17:07 ` Peter Zijlstra
2018-11-29 17:31 ` Andy Lutomirski
2018-11-29 17:35 ` Jiri Kosina
2018-11-29 17:13 ` Steven Rostedt
2018-11-29 17:35 ` Linus Torvalds
2018-11-29 17:44 ` Steven Rostedt
2018-11-29 17:50 ` Linus Torvalds
2018-11-29 17:54 ` Linus Torvalds
2018-11-29 17:58 ` Steven Rostedt
2018-11-29 18:23 ` Linus Torvalds
2018-11-29 18:47 ` Steven Rostedt
2018-11-29 18:58 ` Linus Torvalds
2018-11-29 19:08 ` Linus Torvalds
2018-11-29 19:11 ` Linus Torvalds
2018-12-10 23:58 ` Pavel Machek
2018-12-11 1:43 ` Linus Torvalds
2018-11-29 19:12 ` Steven Rostedt
2018-11-29 19:27 ` Andy Lutomirski
2018-11-29 20:24 ` Josh Poimboeuf
2018-11-29 22:17 ` Josh Poimboeuf
2018-11-29 23:04 ` Linus Torvalds
2018-11-30 16:27 ` Josh Poimboeuf
2018-12-11 9:41 ` David Laight
2018-12-11 17:19 ` Josh Poimboeuf
2018-12-12 18:29 ` Josh Poimboeuf
2018-11-30 16:42 ` Andy Lutomirski
2018-11-30 18:39 ` Josh Poimboeuf
2018-11-30 19:45 ` Linus Torvalds
2018-11-30 20:18 ` Andy Lutomirski
2018-11-30 20:28 ` Steven Rostedt
2018-11-30 20:59 ` Andy Lutomirski
2018-11-30 21:01 ` Steven Rostedt
2018-11-30 21:13 ` Jiri Kosina
2018-11-30 21:10 ` Josh Poimboeuf
2018-11-29 19:16 ` Steven Rostedt
2018-11-29 19:22 ` Josh Poimboeuf
2018-11-29 19:27 ` Steven Rostedt
2018-11-30 22:16 ` Rasmus Villemoes
2018-11-30 22:24 ` Josh Poimboeuf
2018-11-29 19:24 ` Linus Torvalds
2018-11-29 19:28 ` Andy Lutomirski
2018-11-29 19:31 ` Steven Rostedt
2018-11-29 20:12 ` Josh Poimboeuf
2018-11-29 18:00 ` Andy Lutomirski
2018-11-29 18:42 ` Linus Torvalds
2018-11-29 18:55 ` Steven Rostedt
2018-11-29 17:29 ` Linus Torvalds
2018-11-29 17:35 ` Andy Lutomirski
2018-11-26 18:28 ` Andy Lutomirski
2018-11-26 20:14 ` Josh Poimboeuf
2018-11-27 8:46 ` Peter Zijlstra
2018-11-26 16:08 ` Peter Zijlstra
2018-11-26 16:11 ` Ard Biesheuvel
2018-11-26 16:33 ` Andy Lutomirski
2018-11-26 16:39 ` Peter Zijlstra
2018-11-26 16:44 ` Josh Poimboeuf
2018-11-26 14:01 ` [PATCH v2 0/4] Static calls Josh Poimboeuf
2018-11-26 20:54 ` Steven Rostedt
2018-11-26 22:24 ` Josh Poimboeuf
2018-11-26 22:53 ` Steven Rostedt
2018-12-04 23:08 ` Steven Rostedt
2018-12-04 23:41 ` Andy Lutomirski
2018-12-05 15:04 ` Josh Poimboeuf
2018-12-05 23:36 ` Andy Lutomirski
2018-12-07 16:06 ` Edward Cree
2018-12-07 16:49 ` Edward Cree
2018-12-11 18:05 ` Josh Poimboeuf
2018-12-12 5:59 ` Nadav Amit
2018-12-12 17:11 ` Edward Cree
2018-12-12 17:47 ` [RFC/WIP PATCH 0/2] dynamic calls Edward Cree
2018-12-12 17:50 ` [RFC PATCH 1/2] static_call: fix out-of-line static call implementation Edward Cree
2018-12-12 17:52 ` [RFC PATCH 2/2] net: core: rather hacky PoC implementation of dynamic calls Edward Cree
2018-12-12 18:14 ` [PATCH v2 0/4] Static calls Nadav Amit
2018-12-12 18:33 ` Edward Cree
2018-12-12 21:15 ` Nadav Amit
2018-12-12 21:36 ` Edward Cree
2018-12-12 21:45 ` Nadav Amit
2018-12-10 23:57 ` Pavel Machek
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